Elemental mapping by Dawn reveals exogenic H in Vesta's regolith
Science
By: Thomas H. Prettyman, David W. Mittlefehldt, Naoyuki Yamashita, David J. Lawrence, Andrew W. Beck, William C. Feldman, Timothy J. McCoy, Harry Y. McSween, Michael J. Toplis, Timothy N. Titus, Pasquale Tricarico, Robert C. Reedy, John S. Hendricks, Olivier Forni, Lucille Le Corre, Jian-Yang Li, Hugau Mizzon, Vishnu Reddy, Carol A. Raymond, and Christopher T. Russell
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Abstract
Using Dawn’s Gamma Ray and Neutron Detector, we tested models of Vesta’s evolution based on studies of howardite, eucrite, and diogenite (HED) meteorites. Global Fe/O and Fe/Si ratios are consistent with HED compositions. Neutron measurements confirm that a thick, diogenitic lower crust is exposed in the Rheasilvia basin, which is consistent with global magmatic differentiation. Vesta’s regolith contains substantial amounts of hydrogen. The highest hydrogen concentrations coincide with older, low-albedo regions near the equator, where water ice is unstable. The young, Rheasilvia basin contains the lowest concentrations. These observations are consistent with gradual accumulation of hydrogen by infall of carbonaceous chondrites—observed as clasts in some howardites—and subsequent removal or burial of this material by large impacts.
Suggested Citation
Prettyman, T.H., Mittlefehldt, D.W., Yamashita, N., Lawrence, D.J., Beck, A.W., Feldman, W.C., McCoy, T.J., McSween, H.Y., Toplis, M.J., Titus, T.N., Tricarico, P., Reedy, R., Hendricks, J.S., Forni, O., Le Corre, L., Li, J., Mizzon, H., Reddy, V., Raymond, C.A., Russell, C.T., 2012, Elemental mapping by Dawn reveals exogenic H in Vesta's regolith: Science, v. 338, no. 6104, p. 242-246, https://doi.org/10.1126/science.1225354.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Elemental mapping by Dawn reveals exogenic H in Vesta's regolith |
| Series title | Science |
| DOI | 10.1126/science.1225354 |
| Volume | 338 |
| Issue | 6104 |
| Year Published | 2012 |
| Language | English |
| Publisher | AAAS |
| Contributing office(s) | Astrogeology Science Center |
| Description | 5 p. |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Science |
| First page | 242 |
| Last page | 246 |
| Other Geospatial | Vesta |